Why do impact sports disrupt your digestion?

Speeded up digestive transit, abdominals pains, stomach cramp. Your digestive system is having a hard time and lets you know all about it. Why? Type of physical effort, long distance, diet, hydration… ? We review the different possible factors.


1st Factor: The type of physical effort and its mechanical role

Approximately 1 in 2 runners complain about digestive problems. Trail runners, triathletes and marathon runners are often affected. Why? One of the reasons could be mechanical. As a matter of fact, when running over long distances, the impact and bounce can have an effect on the actual function of each organ.

The digestive tract ensures digestion of food and drink. It is made up of the mouth, the throat, the oesophagus, the stomach, the small intestine, the large intestine and the rectum. Each of these parts has a specific function in digestion.

When doing an impact sport, these organs are jostles around, losing their bearings and occasionally there are a few side effects:

- Gastroesophageal reflux linked to the stomach and oesophagus causing acid reflux, sometimes right up into the mouth.

- Nausea and vomiting.

- Stomach cramps.

- Speeding up digestive transit leading to bloating and/or diarrhoea linked to the intestines.

Overstraining abs muscles will also massage your abdomen too much and all the organs within, forcing them to work more. This additional effort is also the source of a sportsperson digestion problems.


2nd Factor: Hydration: Insufficient, too much or inadequate?

Excessively or exclusively drinking water, a sports drink that is not suitable are also part of what causes the occurrence of digestion problems.

Poor hydration can cause a water and mineral salt imbalance. We talk about an electrolyte imbalance.It increases the occurrence of digestion problems.

We recommend alternating water and salt mineral rich drinks (especially sodium) and carbohydrates. Alternating helps to respect the physiological balance and not cause unpleasant symptoms during your race.

For example, in trail running: It is preferable to consume isotonic drinks during a race and exclusively drink water at the drinks station.

Beware of hypertonic drinks! A hypotonic or hypertonic drink is not suitable for our body's physiology. It is always recommended to consume isotonic drinks where the drink's composition is equivalent to the composition of the body's liquids, subsequently enabling optimal assimilation.

When you drink a hypertonic drink, the concentration level is greater than the physiological concentration. Digesting this drink leads to accelerations of digestive transit and abdominal pains. It is, however, recommended if the outdoor temperatures are high.


Dehydration is also a key factor in regulating the digestive system. Drink regularly without waiting to be thirsty!

Also avoid:

- drinks that are too cold, even ice cold. The ideal temperature is between 10 and 15 degrees.

- Energy drinks with stimulating properties.

- Alcohol tends to dehydrate you.

3rd Factor: Food intolerances? Gluten, cows milk… and what if you had an intolerance?

Some of the foods we consume could be inadequately assimilated because of their composition and our ability to digest them. This is what we call food intolerance. Over the medium to long-term, it could be the reason for the occurrence of intestinal inflammation and permeability. This is defined as the passage of substances such as bacteria, toxins, pollutants, additives, etc leaking through the gut wall.

Physical effort accentuates this occurrence. We often mention gluten (present in pasta), lactose (present in dairy products, except if otherwise mentioned on the label). But they can come from any other food, such as almonds, walnuts or even eggs. We are all different with different digestive systems. It's for you to find the food that causes these little or big digestive disruptions and eliminate them from your diet 2 to 3 weeks before the race day.

And what about a quick course of pre or probiotics? Yes!It's the opportunity to take care of your intestines by providing them with small bacteria necessary to help the gut's flora process properly. The healthier your intestinal flora is, the better your intestines work and the better you will digest.

4th Factor: Mesenteric ischemia: What is it?

When doing a sport over a long distance, the blood flow is mainly distributed to the heart and muscles. With the intestines getting an insufficient blood supply, it lacks the oxygen it needs to function properly. Then abdominal pains in the form of cramp or diarrhoea arise, which prevent you from successfully completing your race.

Given this explanation, the only way to prepare your intestines is through training. Little by little, your body will adapt physiologically slowing down the onset of mesenteric ischemia.

5th Factor: Diet: What and when should you eat to prevent digestive disorders during a race?

There are several things to know about diet before throwing yourself into a long effort with impact. Here are a few tips to help you get through the race better:

Tip 1: 3 days before the race day

We recommend limiting the amount of fibre during the 3 days that precede your race. This is because fibres increase the volume of faeces and ferment... Gut discomforts and pain occur when the athlete eats some during the last meal.


Tip 2: Race day

If your last meal contains too much fat or fibre, it slows down digestion with the risk of your stomach not being empty before the start of the race. This will then have an effect on your digestive system.


Tip 3: Chewing

In any event, it is important to be aware of what you are eating and chew properly. As a matter of fact, this favours better assimilation of macro and micronutrients and subsequently reduces digestive problems from happening.


Tip 4: No tests days before race day or on race day

You discover a new food or a new product that seems relevant during the course of a conversation or an search for food supplements or about an idea regarding nutrition in general. There is a big temptation to give it a try and taste it. Big mistake! It is possible that this product or food is not suitable for you and hinders you during the race.

If you are curious, test new things when outside of competition phases.


Tip 5: Alternate your food intake in liquid and solid form

This enables you to limit the gastric volume and facilitates digestion and assimilation of nutrients.

Go with liquid or semi-liquid (gels, stews) during the race and keep solid versions for food/drink stations (bars, dried fruits, etc.).

Over long distances, treat yourself by varying between sweet and salty tastes.

And what about stress?

Friend or foe for sportspeople? Stress can be a friend on the motivational side, helping to secrete adrenaline. It's what makes you want to surpass yourself, achieve your goals, finish off a race or competition. You are at your best thanks to it!

However, it causes a rush of water at the level of the large intestine (colon) and rehydrates the faeces too much, which due to much greater volume, accelerates digestive transit. More often than not, this happens just before the start!

If stress is necessary to achieve our objectives, it useful to control it by taking deep breathes, blanking out thoughts, by using a few essential oils. Keep in mind the enjoyment factor, which is key to success!

Digestion problems are responsible for plenty of withdrawals and counter performances. They are not linked to one single factor. The hard part for a sportsperson is finding all the causes that hinder them and make them suffer.

So take the time, analyse your meals and the reaction of your digestion on the potential bloating, pains or changes in digestive transit that go with it. It helps to better understand what's good for you or not, and sort out.

As a result, you'll learn to manage your stress, to drink properly before, during and after the race.

Feel free to share your experiences with us and why not give us your advice on the subject.